A hybrid vehicle driveline may include a driveline disconnect clutch. The driveline disconnect clutch may be selectively engaged to couple an engine to a motor and other driveline components. The driveline disconnect clutch may be opened during periods of low driver demand torque so that engine rotation may stop while the motor provides torque to control vehicle motion. At times of higher driver demand torque, the driveline disconnect clutch may be closed so that engine torque may be added to motor torque to provide a desired driver demand torque. However, it may be challenging to provide an accurate estimate of driveline torque produced by the engine to meet the driver demand torque.
For example, an engine torque that is estimated solely based on engine speed and load may not be as accurate as is desired due to varying fuel composition, manufacturing tolerances in engine components, system errors (e.g., cam positioning errors), and other conditions that may affect engine torque. Consequently, errors estimating the driveline torque (e.g., a sum of engine and motor torque) may result in a driver demand torque that is greater than or less than a desired driver demand torque. As a result, transmission shifting, driveline disconnect operation, and capability of providing an accurate driver demand torque may degrade.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for operating a hybrid driveline, comprising: adjusting engine torque production in response to a torque transferred across a dual mass flywheel, the torque transferred across the dual mass flywheel responsive to an amount of spring deflection within the dual mass flywheel.
By estimating torque transferred across a dual mass flywheel based on spring deflection, it may be possible to provide the technical result of an improved estimate of engine torque. The improved estimate of engine torque may be the basis for making engine torque adjustments so that driveline torque more closely matches driver demand torque. Additionally, an improved estimate of engine torque as determined from a dual mass flywheel may improve transmission shifting, driveline disconnect clutch operation, and operation of other driveline systems or components that rely on engine torque to provide their desired function.
The present description may provide several advantages. Specifically, the approach may improve hybrid driveline operation. For example, transmission shifting may be improved via having an improved engine torque estimate. Further, the approach may improve engine starting via providing an engine torque estimate while the engine is starting. Further still, the approach may allow for improved engine torque control.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.